Chapare Virus: What to Know About this Rare Viral Hemorrhagic Disease?

History

The first known Chapare outbreak was reported in late 2003 in the rural parts of Chapare Province. The exact number of cases remains unknown. However, healthcare workers at the time documented the clinical descriptions of symptoms and collected a blood sample from a 22-year-old man who had died from this disease.

Initially, the infected individual was suspected of having dengue or yellow fever, but he tested negative for these diseases. He was also tested for the Machupo virus and other related arenaviruses, but these tests also yielded negative results. Detailed sequence analysis of viral RNA definitively identified the new virus as a member of the New World arenaviruses [3]. The virus was then given the name “Chapare virus” in reference to its place of origin.

Epidemiology

The CDC has documented two reported CHHF outbreaks. During the first outbreak, only one CHHF case was confirmed, and this case turned out to be fatal [4]. In 2019, the Bolivian Ministry of Health reported nine cases of hemorrhagic fever from areas around Caranavi and La Paz (Bolivia’s capital). Four of these nine cases had fatal outcomes [5]. 

Hemorrhagic fever caused by the Chapare virus has a 30% fatality rate [6]. The risk of exposure for laboratory and healthcare workers is great [7]. Since the virus is new, there are still many unknowns and much left to discover.

How is it spread?

Since there have only been a few documented cases of Chapare, a great deal of further research is needed to understand exactly how the virus is transmitted [8]. Based on what we know so far, CHHF is probably not an airborne disease [1]. 

CHHF is potentially transmitted through the following ways:

• Direct or indirect contact with the saliva, urine, droppings, bites, and scratches of infected rodents.
• Eating foods contaminated with the saliva, urine, and droppings of infected rodents.
• Inhaling infectious aerosols produced during certain medical procedures on infected people. These procedures include but are not limited to, endoscopy, intubation, suctioning, and chest compressions. 
• Direct contact with the bodily fluids of an infected person, including blood, saliva, urine, semen, and respiratory secretions [8].

Biology of the disease

Scientists are still learning about how the Chapare virus infects humans. Like other arenaviruses, the virus is believed to attack blood vessels and the immune system. Eventually, this can lead to severe bleeding. In extreme cases, the virus is lethal.

How do arenaviruses infect humans?

Arenaviruses that cause viral hemorrhagic fevers can actively replicate in macrophages and dendritic cells. These cells are known as antigen-presenting cells (APCs), a type of immune cell that ingests foreign bodies or potential threats and then “presents” antigens so that the immune system can better recognize these pathogens. This process activates T-cells in our immune system to battle invaders and produce more antibodies. This is how APCs trigger our immune response and help protect us against a wide variety of viruses, bacteria, fungi, and other types of harmful invaders [9]. 

How does the Chapare virus impact the immune system?

When a virus invades and replicates quickly in macrophages and dendritic cells, they trigger the macrophages to release cytokines and chemokines. These signal proteins create a “high alert” to the rest of the immune system and produce both a robust immune response and inflammation. This inflammation leads to higher vascular permeability or leaky blood vessels. In short bursts, this permeability is needed to get immune cells to where they are needed most; however, when this process is prolonged or chronic, it can cause excessive bleeding. 

Higher levels of inflammation also lead to a greater risk of arterial and venous thrombosis  (blocks in arteries and veins due to blood clots). Infected dendritic cells can become impaired, leading to lymphocytic apoptosis [9].

Signs and symptoms

There is limited information about the signs, symptoms, and incubation period of Chapare. However, in general, the incubation period for arenaviruses may range from 4 to 21 days [10]. 

These are the reported signs and symptoms of Chapare hemorrhagic fever (CHHF):

• Fever
• Headache
• Joint pain
• Stomach (abdominal) pain
• Muscle pain
• Pain behind the eyes
• Vomiting
• Diarrhea
• Bleeding gums
• Rashes [1,10]

Diagnosis

CHHF diagnosis should be conducted in laboratories that have the highest levels of biosecurity standards. Stringent protocols are necessary because there is a risk of spreading the virus to healthcare personnel and lab workers. This can lead to even more victims [11]. 

• CHHF virus can be isolated from blood and serum samples during the acute febrile phase of illness. The virus can also be detected in other bodily fluids, including semen, sputum, and urine. 
• Molecular detection assays, like rRT-PCR, have also been effective in diagnosing the disease [3,11].

Treatment

Currently, there is no treatment available to help people diagnosed with CHHF. However, supportive treatment can help manage symptoms and avoid complications. Some of those include:

• Fluid therapy to maintain hydration.
• Treatment to relieve pain and swelling.
• Blood or platelets transfusion (in severe cases).
• Sedative drugs and vasopressin stocks when needed [4].

Prevention

There are no approved vaccines to prevent diseases caused by New World arenaviruses. [12]. There are no vaccines against most viral hemorrhagic fevers. (The two exceptions are yellow fever and Argentine hemorrhagic fever.) 

There are, however, a few preventive measures that can be taken to prevent the spread of viral infections like CCHF. Since CHHF is likely to be a rodent-borne disease, it helps to reduce exposure to rodents. This can be done by:

• Identifying and sealing gaps and holes in houses and buildings.
• Putting rodent traps in and around the property.
• Maintaining clean kitchen surfaces, covering garbage bins, and making food completely inaccessible to rodents.
• Avoiding places infested with rodents. [13].
• Washing fresh produce before eating. [1]

Person-to-person transmission can be prevented by:

• Avoiding contact with the bodily fluids of infected people until they recover entirely and test negative for the virus [13]. This precaution is necessary because infected individuals may continue to shed the virus in bodily fluids for months after recovery [4].
• Taking precautionary measures while performing certain medical procedures on infected people. Infectious aerosols can be generated during the procedure, spreading the viral infection to healthcare workers. 
• Using eye shields when handling or treating infected people or people suspected to be infected by the Chapare virus [13].

Why Study Rare Diseases?

Early detection at point of care

A small outbreak in one corner of the world can spread like wildfire in the blink of an eye. Often, frontline clinicians and healthcare workers are faced with performing the proper differential diagnoses and detecting new infections. 

The study of rare diseases can help advance medical knowledge and enhance differential diagnosis. Viruses are also known to mutate, and keeping an eye on rare, emerging diseases can help detect variants and any new zoonotic spillovers that emerge. In other words, it can help stop a global pandemic! 

Minimize spread of severe illnesses

In general, viral hemorrhagic fevers like Ebola and Marburg can cause severe illness and have high fatality rates. These types of infectious diseases can cause systemic infection, inflammation, damage to blood vessels, and profuse bleeding. Even if outbreaks remain small and infect a few people, they can disrupt lives and cause panic.  

Having reliable data, trained healthcare workers, sufficient medical supplies, and public health initiatives is necessary to control the spread of communicable disease. Public health officials can use this information to create programs that address health disparities for people battling rare infectious diseases and save lives. 

Monitor bioterrorism agents 

The CDC classifies arenaviruses like Lassa and Machupo as Category A bioterrorism agents. This is because many of these viruses have a high fatality rate and can be aerosolized and used to cause a public health crisis. Early symptoms of arenaviruses can also be confused with other infections. This makes early and accurate diagnosis difficult without the right diagnostic tests. 

Accelerate research on infectious diseases

Maintaining a meticulous infectious disease database is a cornerstone of epidemiology. In this age of artificial intelligence (AI), having correct information about outbreaks, no matter how small these outbreaks may be at first, is critical for data modeling of future outbreaks, biomedical research, infectious disease education, public health response, and preventing global pandemics.

One of the biggest challenges researchers face is finding reliable, spatially-resolved data at a country level that is also temporally resolved. Gathering robust data right from the start is essential to help fight against infectious diseases [14].

The GIDEON difference

GIDEON is one of the most well-known and comprehensive global databases for infectious diseases. Data is refreshed daily, and the GIDEON API allows medical professionals and researchers access to a continuous stream of data. Whether your research involves quantifying data, learning about specific microbes, or testing out differential diagnosis tools, GIDEON has you covered with a program that has met standards for excellence.

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